High Mobility Group Nucleosomal Binding Domain 2 (HMGN2) SUMOylation by the SUMO E3 Ligase PIAS1 Decreases the Binding Affinity to Nucleosome Core Particles

Jie Wu,Sol Kim,Man Sup Kwak,Jang Bin Jeong,Hyun Jin Min,Ho-Geun Yoon,Jin-Hyun Ahn,Jeon-Soo Shin

doi:10.1074/jbc.m114.555425

Abstract

High mobility group nucleosomal binding domain 2 (HMGN2) is a small and unique non-histone protein that has many functions in a variety of cellular processes, including regulation of chromatin structure, transcription, and DNA repair. In addition, it may have other roles in antimicrobial activity, cell homing, and regulating cytokine release. Although the biochemical properties of HMGN2 protein are regulated by acetylation and phosphorylation, it is not yet known whether HMGN2 activity can also be regulated by SUMOylation. In this study, we demonstrated for the first time that HMGN2 is modified by covalent attachment of small ubiquitin-related modifier 1 (SUMO1) by pro-inflammatory signal and identified the major SUMOylated lysine residues that localize to the HMGN2 nucleosome-binding domain at Lys-17 and Lys-35. SENP1 can deSUMOylate SUMOylated HMGN2, and PIAS1 is the E3 ligase responsible for SUMOylation of HMGN2. Finally, using SUMO1-conjugated HMGN2 purified from a basal SUMOylation system in Escherichia coli, we demonstrated that SUMOylated HMGN2 has decreased the binding affinity to nucleosome core particles in comparison to unSUMOylated HMGN2. These observations potentially provide new perspectives for understanding the functions of HMGN2 in inflammatory reaction.

Highlights

High mobility group nucleosomal binding domain 2 (HMGN2) is an important nuclear protein that is involved in altering the chromatin structure and facilitating the transcriptional activation
HMGN2 Is SUMOylated in an E. coli Over-expression System— HMGN2 is a ubiquitous non-histone chromosomal protein that plays a role as an architectural element to alter the structure of the chromatic fiber and regulate transcriptional activity [7, 9]
When the double mutant plasmid of K17R/K35R was used for transfection, the SUMOylation band was nearly abolished (Fig. 3B). These results suggest that SUMOylation of HMGN2 in the E. coli system mainly occurs at Lys-17 and Lys35, which are located in the nucleosome binding domain (NBD) region

Summary

Background

HMGN2 is an important nuclear protein that is involved in altering the chromatin structure and facilitating the transcriptional activation. High mobility group nucleosomal binding domain 2 (HMGN2) is a small and unique non-histone protein that has many functions in a variety of cellular processes, including regulation of chromatin structure, transcription, and DNA repair. It may have other roles in antimicrobial activity, cell homing, and regulating cytokine release. There are two major SUMOylated lysine residues located in the HMGN2 nucleosome binding domain, where SUMOylation of HMGN2 dissociates its attachment to nucleosome core particles This suggests that SUMO modification of HMGN2 is a significant factor in the regulation of chromatin structure and function

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION